Stackable storage element



FIG. 1 is a front and side perspective view of a stackable storage element, showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a side elevational view thereof from the left of FIG. 2, the side elevational view from the right of FIG. 2 being the mirror image;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a stackable storage element, as shown and described. 